Vascular diseases, such as atherosclerosis and the like, have become quite prevalent in the modern day. These diseases may manifest themselves in a number of ways, often requiring different forms or methods of treatment for curing the adverse effects of the diseases. Vascular diseases, for example, may take the form of deposits or growths in a patient's vasculature which may restrict, in the case of a partial occlusion, or, stop, in the case of a total occlusion, blood flow to a certain portion of the patient's body. This can be particularly serious if, for example, such an occlusion occurs in a portion of the vasculature that supplies vital organs with blood or other necessary fluids.
To treat these diseases, a number of different therapies have been developed. While a number of effective invasive therapies are available, it is desired to develop non-invasive therapies as well. Non-invasive therapies may be more desirable because of the possibility of decreased chances of infection, reduced post-operative pain, and less post-operative rehabilitation. Drug therapy is one type of non-invasive therapy developed for treating vascular diseases. Clot-busting drugs have been employed to help break up blood clots which may be blocking a particular vascular lumen. Other drug therapies are also available. Further non-invasive intravascular treatments exist that are not only pharmaceutical, but also physically revascularize lumens. Two examples of such intravascular therapies are balloon angioplasty and atherectomy, both of which physically revascularize a portion of a patient's vasculature.
Balloon angioplasty is a procedure wherein a balloon catheter is inserted intravascularly into a patient through a relatively small puncture, which may be located proximate the groin, and intravascularly navigated by a treating physician to the occluded vascular site. The balloon catheter includes a balloon or dilating member which is placed adjacent the vascular occlusion and is then inflated. Intravascular inflation of the dilating member by sufficient pressures, on the order of 5 to 12 atmospheres or so, causes the balloon to displace the occluding matter to revascularize the occluded lumen and thereby restore substantially normal blood flow through the revascularized portion of the vasculature. It is to be noted, however, that this procedure does not remove that matter from the patient's vasculature, but displaces and reforms it.
While balloon angioplasty is quite successful in substantially revascularizing many vascular lumens by reforming the occluding material, other occlusions may be difficult to treat with angioplasty. Specifically, some intravascular occlusions may be composed of an irregular, loose or heavily calcified material which may extend relatively far along a vessel or may extend adjacent a side branching vessel, and thus may not be prone or susceptible to angioplastic treatment. Even if angioplasty is successful, there is a chance that the occlusion may recur. Recurrence of an occlusion may require repeated or alternative treatments given at the same intravascular site.
Accordingly, attempts have been made to develop other alternative mechanical methods of non-invasive, intravascular treatment in an effort to provide another way of revascularizing an occluded vessel and of restoring blood flow through the relevant vasculature. These alternative treatments may have particular utility with certain vascular occlusions, or may provide added benefits to a patient when combined with balloon angioplasty or drug therapies.
One such alternative mechanical treatment method involves removal, not displacement of the material occluding a vascular lumen. Such treatment devices, sometimes referred to as atherectomy devices, use a variety of material removal means, such as rotating cutters or ablaters for example, to remove the occluding material. The material removal device is typically rotated via a drive shaft that extends out of the vascular of the patient and to an electric motor or the like.
In operation, an atherectomy device is typically advanced over a guide wire that is placed in-vivo until the material removal device is positioned just proximal to the occluded site. The motor is then used to rotate both the drive shaft and the material removal device, while the material removal device is moved through the occluded vessel. The material removal device typically ablates the material from the vessel, rather than merely displacing or reforming the material as in a balloon angioplasty procedure.
The guide wire used is subject to greater wear than guide wires used for advancing many other catheters, as the rotating drive shaft is often advanced directly over the guide wire. A stainless steel guide wire is often used, as the surface is sufficiently hard to withstand the wear of the rotating drive shaft. Stainless steel is not sufficiently radiopaque to render the guide wire visible under fluoroscopy however. The guide wire commonly has a distal outer diameter of about 6 thousandths of an inch, and the options for making the narrow wire radiopaque are limited. Gold is radiopaque, but can be too soft to withstand the wear of the rotating drive shaft. Gold can be alloyed, making it harder, but a harder layer over the guide wire can include residual, inner stresses created during manufacture and can also prove too brittle to stand up to repeated flexure through the vasculature.
It would be desirable, therefore, to provide a guide wire that is visible under fluoroscopy, can stand up to the demands of guiding a rotating atherectomy device, and is not likely to develop cracks caused by bending or residual stress. What would be desirable and has not hitherto been provided is a radiopaque guide wire having a harder surface with more flexibility and less residual stress.